The invention pertains to cathode emitter devices. In particular applications, the invention pertains to devices configured to detect infrared radiation, as well as to methods of utilizing such devices.
Many applications are known wherein it is desired to detect and/or image infrared radiation. Exemplary applications include thermo-imaging devices, such as cameras, utilized in night-vision accessories and other surveillance equipment. For instance, infrared radiation can be utilized by surveillance equipment to detect and image objects that are hotter than their surrounding environment. Such utilization takes advantage of the fact that objects naturally emanate infrared radiation when heated (so-called blackbody radiation).
Among the known methods for detecting and/or imaging infrared radiation are methods which take advantage of sensitivity of p-type silicon to infrared radiation. For instance, U.S. Pat. No. 3,814,968 describes a field emission display apparatus comprising an array of lower doped p-type cathode emitter devices in electrical contact with a higher doped p-type semiconductive material. The apparatus is configured such that when the higher doped p-type material is exposed to infrared radiation, the electrical properties of the material change and cause one or more electrons to be emitted from the lower doped p-type cathode array. Such electrons then impact a phosphor spaced from the array to cause a visually detectable image to occur.
A difficulty associated with devices such as that disclosed in U.S. Pat. No. 3,814,968 can be a lack of sensitivity of the semiconductive material to radiation having relatively long wavelengths, such as wavelengths greater than or equal to about 2,500 angstroms. For instance, if p-type doped silicon (with the dopant provided to a concentration of greater than or equal to 1xc3x971018atoms/cm3) is utilized as the semiconductive material, it will typically be unable to detect infrared photons at wavelengths greater than about 1,200nanometers. This causes complications for utilizing silicon detectors because many objects are not hot enough to generate a significant amount of infrared radiation having wavelengths less than or equal to 1,200 nanometers. It would therefore be desirable to develop improved methods for detecting infrared radiation.
In one aspect, a cathode emitter device comprises an infrared receptor having an n-type doped semiconductive region overlying a p-type doped semiconductive region. The n-type and p-type doped regions of the receptor join at a junction diode. The cathode emitter device further comprises an array of cathode emitter tips in electrical connection with the n-type region of the infrared receptor.
In another aspect, the invention encompasses a cathode emitter device. The device includes a substrate comprising an n-type doped region overlying a p-type doped region, with the n-type and p-type doped regions joining at a junction diode. The device further comprises an array of cathode emitter tips in electrical connection with the junction diode, and a receptor assembly beside the junction diode. The receptor assembly comprises a material different from that of the substrate, and comprises a p-type doped region and n-type doped region of said material. The p-type doped region of the receptor assembly contacts the p-type doped region of the substrate, and the n-type doped region of the receptor assembly contacts the n-type doped region of the substrate.
In other aspects, the invention encompasses field emission display devices, such as, for example, devices comprising the above-described cathode emitter device. In yet other aspects, the invention encompasses methods of utilizing cathode emitter devices, such as, for example, methods of utilizing the above-described cathode emitter device.